Modeling of Wire Electrical Discharge Machining ... - IJETAE

International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, Volume 2, Issue 4, April 2012)
It is evident from figure (3a) that the surface roughness
decreases with increase in dielectric pressure, whereas
figure (3b) reveals that the surface roughness increases
with increase in pulse on time. Figure (3c) gives the
variation of surface roughness with voltage corresponding
to minimum and maximum values of pulse on time. It can
be noticed from the figure that corresponding to minimum
value of pulse on time the surface roughness decreases with
increase in voltage, whereas the surface roughness
increases with increase in voltage corresponding to
maximum value of pulse on time.
When the pulse on time is maximum and the voltage
increase from 25 v to 30 v, the surface roughness also
increases. To achieve minimum surface roughness (Ra), the
pulse on time, voltage and dielectric pressure should be set
at 20 µs, 30 V and 15 kgf/cm 2 respectively. The effect of
these factors on surface roughness is evident from the ‗3 D
interaction graph‘ depicted in fig. (4). A contour plot of
surface roughness connecting pulse on time and voltage is
given in fig. (5). On the basis of the experimental
investigations, an empirical relationship for surface
roughness connecting voltage, dielectric pressure and pulse
on time is established, which is given below
FIGURE.4 SURFACE PLOT FOR SURFACE ROUGHNESS.
FIGURE.5 CONTOUR PLOT FOR SURFACE ROUGHNESS.
380
Ra = - 21.54350 + (0.79120 X Voltage) + (2.71630 X
dielectric pressure) + (1.27310 X pulse on time) -
(0.094980 X Voltage X dielectric pressure) – (0.039800 X
Voltage X pulse on time) -(0.13526 X dielectric pressure
X pulse on time) + (4.68400E-003 X Voltage X dielectric
pressure X pulse on time)
VI. COMPARISON OF CONFORMATION TEST
RESULTS WITH PREDICTED VALUES.
Two conformation runs were conducted in order to
measure the reliability of optimization solutions obtained
from the analysis.The comparison of test results between
the therotical prediction and conformation test results were
the final consideration that will determine whether the
optimum parameters predicted are within the allowable
range. The margin of error from prediction and
experimental results was obtained below 7%. Table 3
shows the comparison of the test results with the predicted
values.
TABLE IIIIV
COMPARISON OF THE TEST RESULTS WITH THE THEROTICAL
PREDICTION.
No. of
conformation
Runs
Predicted
values using
the
mathematical
model
Conformation
test results
% of
Error
1 3.77109 3.821 1.32
2 3.63406 3.388 6.76
VII. CONCLUSION
In this study, the machining of Ti-6Al-4V alloy‘s
performance in wire electrical discharge machining is
explored by using two level full factorial experiment.
Design expert was adopted in this study to determine the
optimum condition of machining parameters and the
significance of each parameter on the performance of
machining charectristics.